The development of efficient desorption ionization sources for use with mass spectrometer systems has generated a need for increased accuracy in the determination of the site of desorption of molecules from samples. While the current sampling systems provide the means for selective collection of ions from a spot on the surface they do so without necessarily excluding ions being desorbed from locations adjacent to the sample spot of interest. It can be advantageous to increase the spatial resolution for sampling surfaces without losing sensitivity. Improved resolution in spatial sampling can enable higher throughput analysis and potential for use of selective surface chemistry for isolating and localizing molecules for analysis.